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Focused aperture module

  • US 4,395,676 A
  • Filed: 11/24/1980
  • Issued: 07/26/1983
  • Est. Priority Date: 11/24/1980
  • Status: Expired due to Term
First Claim
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1. A particle analyzing apparatus for detecting properties of particles, said particle analyzing apparatus including a container for holding a liquid suspension of the particles to be analyzed, a first liquid holding chamber, a flow director having a bore which forms a liquid passageway between said container and said first chamber, a second liquid holding chamber, aperture means including a sensing aperture which forms a constricted liquid and electrical passageway between said first chamber and said second chamber, means for providing an electrical current through said sensing aperture to generate detectable electrical signals with the passage of the particles through said sensing aperture, fluid moving means for providing a pressure drop across said sensing aperture to move a quantity of liquid from said first chamber to said second chamber, means for providing a particle free liquid to said first chamber to form a liquid sheath around a quantity of said liquid suspension from said flow director, the improvement comprising:

  • means for providing a substantially constant pressure drop across said flow director to move said quantity of said liquid suspension from said container to said first chamber, whereby said substantially constant pressure drop establishes a substantially constant flow rate of said liquid suspension through said sensing aperture;

    said bore of said flow director having an elongated configuration dimensioned to form a fluid resistor for limiting the flow of said quantity of said suspension through said bore, whereby said fluid resistor sufficiently restrains the flow therethrough to a desired flow rate so as to allow for said pressure drop across said flow director to be of a magnitude that is subject to regulation and measurement.

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